Hydrodynamic rotary seal with opposed tapering seal lips

ABSTRACT

A hydrodynamically lubricating rotary seal for partitioning a lubricant from an environment has a generally circular seal body and sloping, generally opposed projecting static and dynamic sealing lips. The dynamic sealing lip is provided for establishing compressed sealing relation with a relatively rotatable surface, and has a sloping dynamic sealing surface that varies in width, and also has a hydrodynamic inlet curvature that varies in position around the circumference of the seal. 
     When the seal is installed against a relatively rotatable surface, the dynamic sealing lip deforms to define a variable width interfacial contact footprint against the relatively rotatable surface that is wavy on the lubricant side, and wedges a film of lubricating fluid into the interface in response to relative rotation. The environment edge of the interfacial contact footprint is substantially circular, and therefore does not produce a hydrodynamic wedging action in response to relative rotation.

This is a continuation-in-part of utility application Ser. No.09/314,349 filed on May 19, 1999 by Lannie Dietle and Manmohan S. Kalsiand entitled “Hydrodynamic Packing Assembly”. Applicants hereby claimthe benefit of U.S. Provisional Application Serial No. 60/196,323 filedon Apr. 12, 2000 by Lannie L. Dietle and entitled “Hydrodynamic RotarySeal”, and Ser. No. 60/202,614 filed on May 9, 2000 by Lannie L. Dietleentitled “Hydrodynamic Seal”, which provisional applications areincorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates generally to seals that interact withlubricant during rotation of a relatively rotatable surface to wedge afilm of lubricant into the interface between the seal and the relativelyrotatable surface to reduce wear. More specifically, the presentinvention concerns the provision of static and dynamic sealing lips in ahydrodynamic seal that controls interfacial contact pressure within thedynamic sealing interface for efficient hydrodynamic lubrication andenvironmental exclusion while permitting relatively high initialcompression and relatively low torque.

FIG. 1 of this specification represents a commercial embodiment of theprior art of U.S. Pat. No. 4,610,319, and FIG. 1A represents acommercial embodiment of the prior art of U.S. Pat. No. 5,678,829. Thesefigures are discussed herein to enhance the readers' understanding ofthe distinction between prior art hydrodynamic seals and the presentinvention. The lubrication and exclusion principles of FIG. 1 are alsoused in the prior art seals of U.S. Pat. Nos. 5,230,520, 5,738,358,5,873,576, 6,036,192, 6,109,618 and 6,120,036, which are commonlyassigned herewith. The aforementioned patents pertain to various sealproducts of Kalsi Engineering, Inc. of Sugar Land, Tex. that are knownin the industry by the registered trademark “Kalsi Seals”, and areemployed in diverse rotary applications to provide lubricant retentionand contaminant exclusion in harsh environments.

Referring now to FIG. 1, the seal incorporates a seal body 18 that issolid and generally ring-like, and defines a lubricant end 20 and anenvironment end 22. The seal incorporates a dynamic sealing lip 24defining a dynamic sealing surface 26 and also defining a exclusionarygeometry 28 which may be abrupt, and which is for providingenvironmental exclusion.

The dynamic sealing lip 24 has an angulated flank 30 having intersectionwith the seal body at lip termination point 32. Angulated flank 30 isnon-circular, and forms a wave pattern about the circumference of theseal, causing dynamic sealing surface 26 to vary in width.

Hydrodynamic inlet radius 38 is a longitudinally oriented radius that isthe same size everywhere around the circumference of the seal, and istangent to dynamic sealing surface 26 and angulated flank 30. Sincehydrodynamic inlet radius 38 is tangent to angulated flank 30, it alsovaries in position about the circumference of the seal in a wavy manner.Angulated flank 30 defines a flank angle 40 that remains constant aboutthe circumference of the seal. The tangency location 42 betweenhydrodynamic inlet radius 38 and dynamic sealing surface 26 isillustrated with a dashed line.

When installed, the seal is located within a housing groove andcompressed against a relatively rotatable surface to establish sealingcontact therewith, and is used to retain a lubricant and to exclude anenvironment. When relative rotation occurs, the seal remains stationarywith respect to the housing groove, maintaining a static sealingrelationship therewith, while the interface between the dynamic sealinglip 24 and the mating relatively rotatable surface becomes a dynamicsealing interface. The lubricant side of dynamic sealing lip 24 developsa converging relationship with the relatively rotatable surface a resultof the compressed shape of hydrodynamic inlet radius 38.

In response to relative rotation between the seal and the relativelyrotatable surface, the dynamic sealing lip 24 generates a hydrodynamicwedging action that introduces a lubricant film between dynamic sealinglip 24 and the relatively rotatable surface.

The compression of the seal against a relatively rotatable surfaceresults in compressive interfacial contact pressure that is determinedprimarily by the modulus of the material the seal is made from, theamount of compression, and the shape of the seal. The magnitude anddistribution of the interfacial contact pressure is one of the mostimportant factors relating to hydrodynamic and exclusionary performanceof the seal.

The prior art seals are best suited for applications where the pressureof the lubricant is higher than the pressure of the environment. Owingto the complimentary shapes of the seal environment end 22 and themating environment-side gland wall, the seal is well supported by theenvironment-side gland wall in a manner that resists distortion andextrusion of the seal when the pressure of the lubricant is higher thanthe pressure of environment.

If the pressure of the environment is substantially higher than thepressure of the lubricant, the resulting differential pressure-inducedhydrostatic force can severely distort body 18, hydrodynamic inletradius 38 and exclusionary geometry 28. The hydrostatic force pressesbody 18 against the lubricant-side gland wall, and can cause body 18 totwist and deform such that angulated flank 30 and hydrodynamic inletradius 38 are substantially flattened against the relatively rotatablesurface. Such distortion and flatting can inhibit or eliminate theintended hydrodynamic lubrication, resulting in premature seal wearbecause the gently converging relationship between dynamic sealing lip24 and the relatively rotatable surface (which is necessary forhydrodynamic lubrication) can be eliminated. Such distortion can alsocause exclusionary geometry 28 to distort to a non-circularconfiguration and may also cause portions of dynamic sealing surface 26to lift away from the relatively rotatable surface, producing a lowconvergence angle between dynamic sealing surface 26 and the relativelyrotatable surface on the environment edge, and causing the exclusionarygeometry 28 to become non-circular and skewed relative to rotationalvelocity V. Such distorted geometry is eminently suitable for thegeneration of a hydrodynamic wedging action in response to relativerotation of the relatively rotatable surface. Such wedging action canforce environmental contaminants into the sealing interface and causerapid wear.

To effectively exclude a highly pressurized environment, one must use apair of oppositely-facing prior art hydrodynamic seals; one to serve asa partition between the lubricant and the environment, and the other toretain the lubricant, which must be maintained at a pressure equal to orhigher than the environment. This scheme ensures that neither seal isexposed to a high differential pressure acting from the wrong side, butrequires a mechanism to maintain the lubricant pressure at or above theenvironment pressure. For example, see the sealed chambers of theartificial lift pump rod seal cartridge of U.S. Pat. No. 5,823,541, andsee the first pressure stage of the drilling swivel of U.S. Pat. No.6,007,105.

Many applications, such as the oilfield drilling swivel, the progressingcavity artificial lift pump, centrifugal pumps, and rotary miningequipment would benefit significantly from a hydrodynamic rotary sealhaving the ability to operate under conditions where the environmentpressure is higher than the lubricant pressure. The resulting assemblieswould avoid the complexity and expense associated with using pairs ofseals having lubricant pressurization there-between.

In the absence of lubricant pressure, the compressed shape of theenvironment end 22 becomes increasingly concave with increasingcompression because the compression is concentrated at one end of theseal. This reduces interfacial contact pressure near exclusionarygeometry 28 and detracts from its exclusionary performance. In thepresence of differential pressure acting from the lubricant side of theseal, the environment end 22 is pressed flat against the wall of thehousing groove, which increases the interfacial contact pressure nearexclusionary geometry 28 and improves exclusionary performance.

Although such seals perform well in many applications, there are otherswhere increased lubricant film thickness is desired to provide lowertorque and heat generation and permit the use of higher speeds andthinner lubricants. U.S. Pat. No. 6,109,618 is directed at providing athicker film and lower torque, but the preferred, commerciallysuccessful embodiments only work in one direction of rotation, and arenot suitable for applications having long periods of reversing rotation.

Interfacial contact pressure at hydrodynamic inlet radius 38 tends to berelatively high, which is not optimum from a hydrodynamic lubricationstandpoint, and therefore from a running torque and heat generationstandpoint. Hydrodynamic inlet radius 38 is relatively small, andtherefore the effective hydrodynamic wedging angle developed with therelatively rotatable surface is relatively steep and inefficient.

Running torque is related to lubricant shearing action and asperitycontact in the dynamic sealing interface. Although the prior arthydrodynamic seals run much cooler than non-hydrodynamic seals,torque-related heat generation is still a critical consideration. Theprior art seals are typically made from elastomers, which are subject toaccelerated degradation at elevated temperature. For example, mediaresistance problems, gas permeation problems, swelling, compression set,and pressure related extrusion damage all become worse at highertemperatures. The prior art seals cannot be used in some high speed orhigh-pressure applications simply because the heat generated by theseals exceeds the useful temperature range of the seal material.

In many of the prior art seals, interfacial contact pressure decreasestoward exclusionary geometry 28, and varies in time with variations inthe width of the interfacial contact footprint. Neither effect isconsidered optimum for exclusion purposes. When environmentalcontaminant matter enters the dynamic sealing interface, wear occurs tothe seal and the relatively rotatable surface.

A certain minimum level of compression is required so that the seal canaccommodate normal tolerances, misalignment, seal abrasion, and sealcompression set without loosing sealing contact with the relativelyrotatable surface. Seal life is ultimately limited by susceptibility tocompression set and abrasion damage. Many applications would benefitfrom a hydrodynamic seal having the ability to operate with greaterinitial compression, to enable the seal to tolerate greatermisalignment, tolerances, abrasion, and compression set.

Prior art seals can be subject to twisting within the housing groove.Such seals are relatively stable against clockwise twisting, andsignificantly less stable against counter-clockwise twisting, with thetwist direction being visualized with respect to FIG. 1. Commonlyassigned U.S. Pat. Nos. 5,230,520, 5,873,576 and 6,036,192 are directedat helping to minimize such counter-clockwise twisting.

When counter-clockwise twisting occurs, interfacial contact pressureincreases near hydrodynamic inlet radius 38 and decreases nearexclusionary geometry 28, which reduces exclusionary performance. Suchtwisting can also make the seal more prone to skewing within the housinggroove.

U.S. Pat. No. 5,873,576 teaches that typical hydrodynamic seals cansuffer skew-induced wear in the absence of differential pressure,resulting from “snaking” in the gland that is related to circumferentialcompression and thermal expansion. If this snaking/skewing is presentduring rotation, the seal sweeps the shaft, causing environmental mediaimpingement against the seal. U.S. Pat. No. 5,873,576 describes theskew-induced impingement wear mechanism in detail, and describes the useof resilient spring projections to prevent skew. Testing has shown thatthe projections successfully prevent skew-induced wear in the absence ofpressure, as was intended, and as such are an improvement over olderdesigns. However, if the environmental pressure exceeds the lubricantpressure, the differential pressure can, in some embodiments, deform theseal in ways that are less favorable to environmental exclusion.

Referring now to the prior art illustration of FIG. 1A, there is shown across-sectional view of a prior art seal representative of thecommercial embodiment of U.S. Pat. No. 5,678,829. Features in FIG. 1Athat are represented by the same numbers as those in FIG. 1 have thesame function as the features of FIG. 1. Solid lines represent theuninstalled cross-sectional condition of the seal, and dashed linesrepresent the installed cross-sectional condition; note the twistedinstalled condition.

An annular recess 49 defines flexible body lips 52 and 55, one of whichincorporates the dynamic sealing surface 26, angulated flank 30,hydrodynamic inlet radius 38, and exclusionary geometry 28. Thereduction of interfacial contact pressure near the circular exclusionarygeometry 28 is particularly severe in such seals because of the hingingof the flexible body lips, which angularly displaces the dynamic sealingsurface 26 and exclusionary geometry 28. This tends to “prop up” theexclusionary geometry 28 as shown, minimizing its effectiveness.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to generally circular rotary shaft sealssuitable for bi-directional rotation that are used to partition a firstfluid from an second fluid, and that exploit the first fluid as alubricant to lubricate at a dynamic sealing interface. It is preferredthat the first fluid be a liquid-type lubricant, however in some casesother fluids such as water or non-abrasive process fluid can be used forlubrication. The second fluid may be any type of fluid, such as a liquidor gaseous environment or a process media, or even a vacuum-typeenvironment.

The seal of the present invention is positioned by a machine elementsuch as a housing, and compressed against a relatively rotatablesurface, initiating sealing therebetween. The machine element may definea circular seal groove for positioning the seal. When relative rotationoccurs, the seal preferably maintains static sealing with the machineelement, and the relatively rotatable surface slips with respect to theseal at a given rotational velocity. (Alternate embodiments are possiblewherein the seal can slip with respect to both the machine element andthe relatively rotatable surface.) The seal defines generally opposedfirst and second seal ends, and incorporates a dynamic sealing lip and astatic sealing lip of generally circular configuration that are ingenerally opposed relation to one another to minimizecompression-induced twisting of the seal cross-section. The dynamicsealing lip defines a sloping dynamic sealing surface of variable widthand a hydrodynamic inlet curvature of variable position. The staticsealing lip defines a sloping static sealing surface for establishingstatic sealed relationship with the machine element, and is in generallyopposed relation to the sloping dynamic sealing surface.

The variation in position of the hydrodynamic inlet curvature may besinusoidal, or any other suitable repetitive or non-repetitive patternof variation. The hydrodynamic inlet curvature can consist of any typeor combination of curve, such a radius, and portions of curves such asellipses, sine waves, parabolas, cycloid curves, etc.

The sloping dynamic sealing surface and the variable positionhydrodynamic inlet curvature deform when compressed into sealingengagement against the relatively rotatable surface to define ahydrodynamic wedging angle with respect to the relatively rotatablesurface, and to define an interfacial contact footprint of generallycircular configuration but varying in width, being non-circular on thefirst footprint edge due to the aforementioned variations. Thenon-circular (i.e. wavy) first footprint edge hydrodynamically wedges alubricating film of the first fluid into the interfacial contactfootprint in response to a component of the relative rotationalvelocity, causing it to migrate toward the second footprint edge. Thefirst footprint edge is sometimes referred to as the “lubricant side” or“hydrodynamic edge”, and the second footprint edge is sometimes referredto as the “environment side” or “exclusion edge”. The number andamplitude of the waves at the first footprint edge can vary as desired.The relatively rotatable surface can take any suitable form, such as anexternally or internally oriented cylindrical surface, or asubstantially planar surface, without departing from the spirit or scopeof the invention.

The seal provides a dynamic exclusionary intersection of abrupt formthat provides the interfacial contact footprint with a second footprintedge, sometimes called the “environment edge”, that is substantiallycircular to prevent hydrodynamic wedging action and resist environmentalexclusion. In the preferred embodiment, the dynamic exclusionaryintersection is an intersection between the sloping dynamic sealingsurface and the second seal end.

In the preferred embodiment, an energizer of a form common to the priorart having a modulus of elasticity different from the seal body, such asan elastomeric ring, a garter spring, a canted coil spring, or acantilever spring, is provided to load the dynamic sealing lip againstthe relatively rotatable surface. In simplified embodiments, theenergizer can be eliminated, such that the seal has one or more flexiblelips, or such that the seal is solid and consists of a single material.

The second seal end is curved outward in a generally convexconfiguration in the uncompressed shape. When the seal is installed, theconvex shape changes to a more straight configuration that helps tomaintain contact pressure at the second edge of the interfacial contactfootprint.

The generally circular body of the preferred seal embodiment defines adynamic control surface and a static control surface near the first sealend that are in generally opposed relation to one another, and can reactrespectively against the relatively rotatable surface and the machineelement to minimize undue twisting of the installed seal, which helps tomaintain adequate interfacial contact pressure at the second footprintedge, thereby facilitating resistance to intrusion of abrasives that maybe present in the second fluid.

The preferred seal cross-section defines a depth dimension from thesloping dynamic sealing surface to the sloping static sealing surface,and also defines a length dimension from the first seal end to secondseal end. In the preferred embodiment of the present invention, theratio of the length dimension divided by the depth dimension ispreferred to be greater than 1.2 and ideally is in the range of about1.4 to 1.6 to help minimize seal cross-sectional twisting.

The seal can be configured for dynamic sealing against a shaft, a bore,or a face. Simplified embodiments are possible wherein one or morefeatures of the preferred embodiment are omitted.

It is one object of this invention to provide a hydrodynamic rotary sealhaving low torque and efficient exclusionary performance for reducedwear and heat generation. It is a further object to provide a seal thatcan operate with relatively high compression to better resist abrasivesand tolerate runout, misalignment, tolerances, and compression set.

Another object is to compress a sloping dynamic sealing surface of ahydrodynamic seal against a relatively rotatable surface to establish aninterfacial contact footprint, whereby more compression and interfacialcontact pressure occurs at a second footprint edge, and less compressionand interfacial contact pressure occurs at a first footprint edge.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

So that the manner in which the above recited features, advantages, andobjects of the present invention are attained and can be understood indetail, a more particular description of the invention, brieflysummarized above, may be had by reference to the embodiments thereofwhich are illustrated in the appended drawings.

It is to be noted, however, that the appended drawings only illustratetypical embodiments of this invention, and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

In the Drawings:

FIG. 1 is a sectional view of a hydrodynamic seal representing the priorart and embodying the subject matter of U.S. Pat. No. 4,610,319;

FIG. 1A is a sectional view of a hydrodynamic seal representing theprior art and embodying the subject matter of U.S. Pat. No. 5,678,829.

FIG. 2 is a fragmentary cross-sectional view representing thecross-sectional configuration of a ring shaped hydrodynamic sealembodying the principles of the present invention when located in acircular seal groove defined by a machine component and compressedagainst a relatively rotatable surface;

FIG. 2A is a fragmentary cross-sectional view of an uncompressedhydrodynamic seal embodying the principles of the present invention asconfigured for sealing against a relatively rotatable externalcylindrical surface such as a shaft;

FIG. 2B is a fragmentary cross-sectional view of an uncompressedhydrodynamic seal embodying the principles of the present invention asconfigured for sealing against a relatively rotatable internalcylindrical surface;

FIG. 2C is a fragmentary cross-sectional view of an uncompressedhydrodynamic seal as configured for sealing against a relativelyrotatable planar surface for applications where the seal lubricant isinterior of the dynamic sealing lip;

FIG. 2D is a fragmentary cross-sectional view of an uncompressedhydrodynamic seal as configured for sealing against a relativelyrotatable planar surface for applications where the seal lubricant isexterior to the dynamic sealing lip;

FIG. 3 is a fragmentary cross-sectional view of a simplification of theinvention wherein the seal is solid and is constructed from a singlematerial;

FIG. 4 is a fragmentary cross-sectional view of a simplification of theinvention wherein the seal is constructed from a single material anddefines flexible sealing lips;

FIG. 5 is a fragmentary cross-sectional view of an alternate embodimentof the invention wherein the seal incorporates an insertable resilientenergizer;

FIG. 6 is a fragmentary cross-sectional view of an alternate embodimentof the invention wherein the seal incorporates a coil spring energizer;

FIG. 7 is a fragmentary cross-sectional view of an alternate embodimentof the invention wherein the seal incorporates a cantilever springenergizer;

FIG. 8 is a fragmentary cross-sectional view of an alternativeembodiment of the invention wherein the seal incorporates a dynamicsealing lip made from a material having a predetermined modulus ofelasticity and the energizer is made of a material having a modulus ofelasticity that is less than that of the dynamic sealing lip;

FIG. 9 is a fragmentary cross-sectional view of an alternativeembodiment of the invention wherein the dynamic control surface and thestatic control surface have been eliminated all the way back to thedynamic sealing lip and leaving the first end non-circular; and

FIG. 10 is a fragmentary cross-sectional view of an alternativeembodiment of the invention where two dynamic sealing lips are provided.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 2-2D represent the preferred embodiment of the present invention.FIG. 2 represents the cross-sectional configuration of the seal wheninstalled. FIGS. 2A and 2B represent the uninstalled cross-sectionalconfiguration of the preferred embodiment as configured for radialsealing. FIGS. 2C and 2D represent the uninstalled cross-sectionalconfiguration of the preferred embodiment as configured for axialsealing. Features throughout this specification that are represented bylike numbers have the same function. For orientation purposes, it shouldbe understood that in the cross-sections of FIGS. 2-2D, and otherfigures herein, the cross-section of the respective cutting planespasses through the longitudinal axis of the seal.

In FIG. 2, a fragmentary transverse cross-sectional view is shownrepresenting the cross-sectional configuration of the preferredembodiment of the hydrodynamic seal 103 of the present invention whenlocated in and positioned by a circular seal groove 106 defined by afirst machine component 109 (such as a housing) and compressed betweengroove counter-surface 112 of circular seal groove 106 and relativelyrotatable surface 115 of a second machine component 118. This initiatesa static sealing relationship with groove counter-surface 112 andrelatively rotatable surface 115 in the same manner as any conventionalinterference type seal, such as an O-Ring. Groove counter-surface 112and relatively rotatable surface 115 are in generally opposed relationto one-another. Machine component 109 and machine component 118 togethertypically define at least a portion of a chamber for locating a firstfluid 121. The compressed configuration of the hydrodynamic seal 103shown in FIG. 2 is representative of its shape when the pressure offirst fluid 121 is substantially the same as the pressure of secondfluid 124.

Circular seal groove 106 also preferably includes a first groove wall119 and a second groove wall 120 that are in generally opposed relationto one another. In the hydrodynamic seal industry, first groove wall 119is often referred to as the “lubricant-side gland wall”, and secondgroove wall 120 is often referred to as the “environment-side glandwall”. Although first groove wall 119 and second groove wall 120 areshown to be in fixed, permanent relation to one another, such is notintended to limit the scope of the invention, for the invention admitsto other equally suitable forms. For example, first groove wall 119and/or second groove wall 120 could be configured to be detachable frommachine component 109 for ease of maintenance and repair, but thenassembled in more or less fixed location for locating the seal.

Hydrodynamic seal 103, which is of generally ring-shaped configuration,has an annular seal body 104 that is used to partition the first fluid121 from the second fluid 124, and to prevent intrusion of the secondfluid 124 into the first fluid 121. The first fluid 121 is exploited inthis invention to lubricate the dynamic sealing interface, and ispreferably a liquid-type lubricant such as a synthetic or natural oil,although other fluids including greases, water, and various processfluids are also suitable for lubrication of the seal in someapplications. The second fluid 124 may be any type of fluid desired,such as a lubricating media, a process media, an environment, etc.Relatively rotatable surface 115 can take the form of an externally orinternally oriented substantially cylindrical surface, as desired, withhydrodynamic seal 103 compressed radially between groove counter-surface112 and relatively rotatable surface 115. Alternatively, relativelyrotatable surface 115 can take the form of a substantially planarsurface, with hydrodynamic seal 103 compressed axially between a groovecounter-surface 112 and relatively rotatable surface 115 ofsubstantially planar form. Illustrations of the preferred embodiment asconfigured for radial compression are shown in FIGS. 2A and 2B.Illustrations of the preferred embodiment as configured for axialcompression are shown in FIGS. 2C and 2D.

Hydrodynamic seal 103 incorporates a dynamic sealing lip 127 and astatic sealing lip 128 that are of generally circular configuration, andin generally opposed relation to one another as shown, to minimize thepotential for twisting of the seal within the gland. It is preferredthat the uninstalled profile of the static sealing lip 128 mimic theaverage profile of the dynamic sealing lip 127 to provide a degree ofcompressive symmetry, although the overall projection of the two lipsneed not be identical.

Hydrodynamic seal 103 defines a sloping dynamic sealing surface 140which is disposed in facing relation with the relatively rotatablesurface 115, and which in the uncompressed condition, is sloped inregard to the relatively rotatable surface and hydrodynamic seal 103also defines a hydrodynamic inlet curvature 142 for facing therelatively rotatable surface 115. Hydrodynamic inlet curvature 142 ispreferred to be constant in curvature, but varies in position around thecircumference of hydrodynamic seal 103, causing the width of slopingdynamic sealing surface 140 to vary. The slope of sloping dynamicsealing surface 140 is preferred to be constant around the circumferenceof hydrodynamic seal 103, and the cross-sectional profile of slopingdynamic sealing surface 140 can be any suitable shape, includingstraight or curved lines or line combinations. The blend location 141between hydrodynamic inlet curvature 142 and sloping dynamic sealingsurface 140 is represented by a dashed line in FIGS. 2A, 2C, and 3-10.In the preferred embodiment, blend location 141 is a location oftangency between hydrodynamic inlet curvature 142 and sloping dynamicsealing surface 140.

The non-circular, wavy positional variation of hydrodynamic inletcurvature 142 can take any form which is skewed with respect to thedirection of relative rotation, and could take the form of one or morerepetitive or non-repetitive convolutions/waves of any form including asine, saw-tooth or square wave configuration, or plural straight orcurved segments forming a tooth-like pattern, or one or more paraboliccurves, cycloid curves, witch/versiera curves, elliptical curves, etc.or combinations thereof, including any of the design configurationsshown in U.S. Pat. No. 4,610,319, and U.S. patent application Ser. No.09/073,410.

Hydrodynamic seal 103 also defines sloping static sealing surface 131which is generally circular and in generally opposed relation to slopingdynamic sealing surface 140 and which, in the noncompressed conditionthereof, is of sloped configuration. A static exclusionary intersection151 is preferably provided at the intersection between second seal end136 and sloping static sealing surface 131 for excluding the secondfluid 124. Both sloping dynamic sealing surface 140 and sloping staticsealing surface 131 are angulated with respect to the respective matingsurfaces of the machine components 118 and 109. The sloping staticsealing surface 131 defines a lubricant side edge 132 and an environmentside edge which is established by a static exclusionary intersection151.

The cross-section of hydrodynamic seal 103 defines an annular seal body104 having a first seal end 133 for facing the first groove wall 119shown in FIG. 2 and also defines a second seal end 136 for facing secondgroove wall 120 shown in FIG. 2. In the hydrodynamic seal industry,first seal end 133 is often referred to as the “lubricant end”, andsecond seal end 136 is often referred to as the “environment-end”. Thefirst seal end 133 of the seal cross-section is preferred to be ingenerally opposed relation to the second seal end, and it is preferredthat the second seal end 136 be curved outward as shown in a generallyconvex shape, in the uninstalled condition. The generally convex shapecan consist of one or more curves, or can be approximated by straightlines. Installation of hydrodynamic seal 103 compresses dynamic sealinglip 127 against the relatively rotatable surface 115 and establishes aninterfacial contact footprint of generally circular form and having awidth dimension W which varies in size about the circumference ofhydrodynamic seal 103. Sloping dynamic sealing surface 140, in thepreferred embodiment, extends in sloping fashion from dynamicexclusionary intersection 139 to hydrodynamic inlet curvature 142, andcan be comprised of any suitable sloping shape or combination of slopingshapes as desired, including straight and curved shapes. The geometry ofhydrodynamic inlet curvature 142 can take any suitable designconfiguration that results in a gradually converging, non-circulargeometry for promoting hydrodynamic wedging without departing from thespirit or scope of the present invention, including any type of curve,such as but not limited to a radius, a portion of an ellipse, a portionof a sine wave curve, a portion of a parabolic curve, a portion of acycloid curve, a portion of witch/versiera curves, or combinationsthereof, etc.

The annular seal body 104 of hydrodynamic seal 103 defines a dynamiccontrol surface 145 for facing the relatively rotatable surface 115 thatis shown in FIG. 2, and also defines a static control surface 148 forfacing the groove counter-surface 112 that is shown in FIG. 2. Dynamiccontrol surface 145 cooperates with the relatively rotatable surface andstatic control surface 148 cooperates with the circular seal groove toprevent undue twisting of the installed seal within the seal groove.

Hydrodynamic seal 103 defines a depth dimension D from sloping staticsealing surface 131 to sloping dynamic sealing surface 140, and alsodefines a Length dimension L from first seal end 133 to second seal end136. Dynamic exclusionary intersection 139 is preferably an abruptexclusionary geometry adapted to be exposed to the second fluid 124 forexcluding intrusion of second fluid 124. Dynamic exclusionaryintersection 139 is located by a positional dimension P from bodyintersection 154. Length dimension L and positional dimension P arepreferred to be constant about the circumference of hydrodynamic seal103. In the preferred embodiment, owing to the preferred curvature ofsecond seal end 136, positional dimension P is less than Lengthdimension L, however it is understood that these dimensions could besubstantially equal if the uninstalled curvature of second seal end 136is small or substantially absent.

When relative rotation is absent, a liquid tight static sealingrelationship is maintained at the interface between static sealing lip128 and groove counter-surface 112, and at the interface between dynamicsealing lip 127 and relatively rotatable surface 115. When relativerotation occurs between circular seal groove 106 and relativelyrotatable surface 115, the hydrodynamic seal 103 remains stationary withrespect to groove counter-surface 112 and maintains a static sealingrelationship therewith, while the interface between dynamic sealing lip127 and relatively rotatable surface 115 becomes a dynamic sealinginterface such that relatively rotatable surface 115 slips with respectto dynamic sealing lip 127 at a given rotational velocity “V”. Therelative rotation direction is normal (perpendicular) to the plane ofthe cross-section depicted in FIG. 2.

In the installed condition, dynamic sealing lip 127 deforms to establishan interfacial contact footprint against relatively rotatable surface115. This footprint has a width dimension W (see FIG. 2) that varies insize about the circumference of hydrodynamic seal 103 due to thepositional variation of the hydrodynamic inlet curvature 142. The firstfootprint edge 157 of the interfacial contact footprint is non-circular;i.e. wavy, due to the positional variation of the hydrodynamic inletcurvature 142 and, in conjunction with the deformed shape of dynamicsealing lip 127, produces a hydrodynamic wedging action in response torelative rotation between the hydrodynamic seal 103 and the relativelyrotatable surface 115. This hydrodynamic wedging action wedges a film oflubricating fluid (i.e. first fluid 121) into the interfacial contactfootprint between the dynamic sealing lip 127 and the relativelyrotatable surface 15 for lubrication purposes, which reduces wear,torque and heat generation.

The first footprint edge 157 will be shaped in a wave pattern similar tothe wave pattern of blend location 141, but may occur on either the leftor right side of blend location 141, depending on the magnitude of sealcompression, swelling and thermal expansion; etc. It can be appreciatedthat if the first footprint edge 157 occurs on the sloping dynamicsealing surface 140, the resulting hydrodynamic wedging angle will bemore efficient than if the first footprint edge 157 occurs on thehydrodynamic inlet curvature 142. It can also be appreciated that thehydrodynamic inlet curvature 142 helps to limit the ultimate width thatthe interfacial contact footprint can achieve, and therefore helps tomitigate the effects that compression variations, swelling, thermalexpansion, etc. have on footprint width dimension W.

The number and amplitude of the waves at the first footprint edge 157can be varied to achieve the desired hydrodynamic lubricant filmthickness by varying the wave number and amplitude of the wavypositional variation of hydrodynamic inlet curvature 142. The generalinterfacial contact footprint shape (wavy on one side, circular on theother) is in accordance with the teachings of U.S. Pat. No. 4,610,319,but the interfacial contact pressure profile that is achieved with thesloping surfaces of the present invention is far superior, as is theexclusionary performance of the seal.

The second footprint edge 160 (sometimes called the “environment edge”)of the interfacial contact footprint is substantially circular, andtherefore does not produce a hydrodynamic wedging action in response torelative rotation between the hydrodynamic seal 103 and the relativelyrotatable surface 115, thereby facilitating exclusion of second fluid124.

Owing to the angled nature of sloping dynamic sealing surface 140 andsloping static sealing surface 131, when hydrodynamic seal 103 isinstalled, more compression occurs at the second footprint edge 160 ofthe interfacial contact footprint (where more compression is desirableto compensate for abrasive wear resulting from exposure to any abrasivesthat may be present in the second fluid 124) and less compression occursat the first footprint edge 157 of the interfacial contact footprint.This means that interfacial contact pressure within the interfacialcontact footprint between the dynamic sealing lip 127 and the relativelyrotatable surface 115 can easily be engineered to be less at firstfootprint edge 157 and significantly greater at second footprint edge160.

The preferably abrupt angle of convergence at dynamic exclusionaryintersection 139 provides a rapid rise in contact pressure at the secondfootprint edge 160. Compression of sealing material in compressiveregion C (which in the uninstalled state overhangs past dynamicexclusionary intersection 139) further adds to the magnitude ofinterfacial contact pressure near second footprint edge 160, andtherefore enhances exclusionary performance.

As noted previously, the installed shape of the environment end of priorart seals becomes somewhat concave in the absence of pressure,particularly at high levels of compression. This reducesenvironment-edge interfacial contact pressure, and reduces exclusionaryperformance. In the present invention, this problem is addressed bymaking the second seal end 136 of the cross-section generally convex, sothat when hydrodynamic seal 103 is installed, the second seal end 136becomes approximately straight. The compressive reaction caused by theangle of sloping dynamic sealing surface 140 and sloping static sealingsurface 131 tends to exaggerate the formation of a concave second sealend 136 under compression unless this tendency is addressed byimplementing the convex end shape shown.

Because the seal of the present invention has high levels of compressionand contact pressure near the second footprint edge 160, it resistsintrusion of the second fluid 124, and provides dimensionally morematerial to sacrifice to abrasion, allowing long service life in thepresence of abrasives within second fluid 124. The high compression alsohelps to make the seal tolerant of runout, misalignment, tolerances, andcompression set.

It has previously been mentioned that the present invention is suitablefor both radial compression arrangements and axial compressionarrangements. In the case of very large diameter seals, sloping dynamicsealing surface 140 and dynamic control surface 145 can simply bemanufactured as a generally internally oriented surfaces, with slopingdynamic sealing surface 140 configured for sealing against a relativelyrotatable surface 115 defining an externally oriented cylindricalsurface. The cross-section of large diameter seals can be rotated 90degrees so that sloping dynamic sealing surface 140 becomes a generallyaxially oriented surface configured for sealing against a relativelyrotatable surface 115 of substantially planar form, or can be rotated180 degrees so that sloping dynamic sealing surface 140 becomes anexternally oriented surface configured for sealing against a relativelyrotatable surface 115 defining an internally oriented cylindricalsurface. The relative torsional stiffness of small diameter seals ismuch higher, and for small seals the sloping dynamic sealing surface 140should be pre-oriented in the desired configuration at the time ofmanufacture.

Radial compression of seals not only causes radial compression, but alsocauses a certain amount of circumferential compression that can causeunpressurized seals to twist and skew (i.e. snake) within the gland. Insuch cases, the sealing slip “sweeps” the shaft, causing environmentalimpingement and seal wear. Circumferential compression-induced skewingis in part related to what proportion of the seal is being initiallycompressed, the magnitude of compression, how stiff the cross-section isproportional to the diameter, and how the thermal expansion of the sealis constrained.

In the preferred embodiment shown, when used in radial compression, onlya relatively small percentage of the seal body is subject to compressionbetween relatively rotatable surface 115 and groove counter-surface 112,therefore in radial compression applications, only a relatively smallportion of the seal is circumferentially compressed. A much largerportion of the seal is not circumferentially compressed, and thereforeserves to inhibit circumferential compression-induced skewing. Further,the construction of the seal, owing to the longer than usual lengthdimension L, is relatively stiff compared to prior art seals, whichhelps to inhibit local buckling-induced skew.

In the preferred embodiment of the present invention, the ratio oflength dimension L divided by depth dimension D is preferred to begreater than 1.2 and ideally is in the range of about 1.4 to 1.6. Manystyles of prior art seals are prone to significantly reduced interfacialcontact pressure near second footprint edge 160 upon torsional twistingof the seal cross-section within the seal groove. In the preferredembodiment of the present invention, owing to the ratio of lengthdimension L divided by depth dimension D, the dynamic control surface145 will contact relatively rotatable surface 115 to prevent furthercross-sectional twisting before a significant reduction in interfacialcontact pressure near second footprint edge 160 can occur.

In the prior art seals, interfacial contact pressure at the environmentedge of the footprint varied in time with the waves. In the preferredembodiment of the present invention, as the width dimension W of theinterfacial contact footprint changes locally due to the varyingposition of the hydrodynamic inlet curvature 142, the interfacialcontact pressure at the second footprint edge 160 remains more constantbecause the depth dimension D of the seal can be engineered to varylocally in time with the width dimension W to even out the contactpressure variations around the circumference of the seal. If depthdimension D is made to vary, either static exclusionary intersection 151or dynamic exclusionary intersection 139 (or both) must necessarily benon-circular in the uninstalled condition of the seal. A molding flashline is typically located at both static exclusionary intersection 151and dynamic exclusionary intersection 139. Non-circularity caused byvariations in depth dimension D affects the accuracy of flash trimmingoperations. Since dynamic exclusionary intersection 139 defines thesecond footprint edge 160 of the interfacial contact footprint, which isdesired to be circular for optimum exclusion resistance, it is preferredthat dynamic exclusionary intersection 139 be manufactured circular tomaximize the accuracy of flash removal operations at that location.Therefore it is preferred that for any embodiment herein where depthdimension D varies, the static exclusionary intersection 151 be madenon-circular, since any inaccuracy in flash removal operations at thatlocation has minimal effect on seal performance. It can be appreciated,however, that in applications where no flash line exists at dynamicexclusionary intersection 139, that intersection can be madenon-circular as a result of variations in depth dimension D, yet when itis installed against a relatively rotatable surface, the resultingsecond footprint edge 160 will be substantially circular.

The dynamic sealing lip 127 is constructed of a sealing materialselected for its wear and extrusion resistance characteristics, and hasa predetermined modulus of elasticity. In the preferred embodiment ofthe present invention, an energizer 163 is provided to load slopingdynamic sealing surface 140 against relatively rotatable surface 115 andto load sloping static sealing surface 131 against groovecounter-surface 112. The energizer 163 can take any of a number ofsuitable forms known in the art, including various forms of springswithout departing from the scope or spirit of the invention, as will bediscussed later. The annular recess 167 can also be of any suitableform.

As shown in FIGS. 2-2D, energizer 163 can be a resilient material thathas a modulus of elasticity which may be different than thepredetermined modulus of elasticity of the dynamic sealing lip 127. Forexample, the modulus of elasticity of energizer 163 could be lower thanthe predetermined modulus of elasticity of dynamic sealing lip 127 inorder to manage interfacial contact pressure to optimum levels forlubrication and low torque. Energizer 163 may be bonded to or integrallymolded with the rest of the seal to form a composite structure, or canbe simply be a separate piece mechanically assembled to the rest of theseal. Other suitable types of energizers are shown in subsequentfigures. The energizer 163 shown in the various figures herein can be ofany of the various types of energizer discussed herein without departingfrom the spirit or scope of the invention. The hydrodynamic seal 103 ofFIGS. 2-2D is illustrated as a compression-type seal, but can beconverted to a flexing lip type seal by elimination of the energizer163, as can the other seal figures herein that illustrate an energizer163 that is contained within an annular recess 167.

FIGS. 2A-2D show that the basic concept of the preferred embodiment canbe configured for dynamic sealing against a shaft, a bore, or a facewithout departing from the spirit or essence of the invention.

FIG. 2A is a fragmentary cross-sectional view of uninstalledhydrodynamic seal 103 for being compressed in a radial direction forsealing against a relatively rotatable surface of external cylindricalform, such as a the exterior surface of a shaft. Sloping dynamic sealingsurface 140, hydrodynamic inlet curvature 142 and dynamic controlsurface 145 are generally internally oriented surfaces, with slopingdynamic sealing surface 140 configured for sealing against an externalcylinder.

FIG. 2B is a fragmentary cross-sectional view of uninstalledhydrodynamic seal 103 as configured for being compressed in a radialdirection for sealing against a relatively rotatable surface of internalcylindrical form, such as a bore. Sloping dynamic sealing surface 140,hydrodynamic inlet curvature 142 and dynamic control surface 145 areexternally oriented surfaces, with sloping dynamic sealing surface 140configured for sealing against a bore.

FIGS. 2C and 2D are fragmentary cross-sectional views of uninstalledhydrodynamic seal 103 as configured for being compressed in a an axialdirection for sealing against a relatively rotatable surface ofsubstantially planar form, and clearly illustrate that the presentinvention may be also used in a face-sealing arrangements. Slopingdynamic sealing surface 140, hydrodynamic inlet curvature 142 anddynamic control surface 145 are generally axially oriented surfaces,with sloping dynamic sealing surface 140 configured for sealing againsta face. In FIG. 2C the sloping dynamic sealing surface 140, hydrodynamicinlet curvature 142 and dynamic exclusionary intersection 139 arepositioned for having the first fluid 121, i.e. a lubricating fluid,toward the inside of the seal, and in FIG. 2D they are positioned forhaving the first fluid 121 toward the outside of the seal.

Though the preferred embodiment of FIGS. 2-2D incorporates a dynamicsealing lip made from one material, and an energizer made from anothermaterial, such is not intended to limit the present invention in anymanner whatever. It is intended that the seal of the present inventionmay incorporate one or more seal materials or components withoutdeparting from the spirit or scope of the invention.

In FIG. 3, the energizing section of the preferred embodiment has beeneliminated by simply constructing the seal as a solid, generallycircular seal composed of resilient sealing material, such as anelastomer. This results in simplified manufacture and lower cost, andpotentially better dimensional accuracy at depth dimension D.

In FIG. 4, the energizing section of the preferred embodiment has beeneliminated, leaving a void in the form of an annular recess 167 wherethe energizing section would otherwise be, and the resulting seal is ofthe flexing-lip type. Annular recess 167 defines dynamic sealing lip 127and static sealing lip 128 to be of the flexing lip variety. The seal ofFIG. 4 is superior in abrasion resistance, compared to the sealsdisclosed in U.S. Pat. No. 5,678,829, because of the slope of slopingdynamic sealing surface 140 prevents the lifting/propping of thecircular exclusionary geometry that occurs in the prior art sealsdisclosed in U.S. Pat. No. 5,678,829. The flexible lip constructionpermits the use of relatively high modulus materials that wouldotherwise be unsuitable for use in a solid (ungrooved) seal due to thehigh interfacial contact pressure that would result.

The contact pressure at the interface between the dynamic sealing lip127 and the mating relatively rotatable surface is one of severalimportant factors controlling hydrodynamic performance because itdirectly influences hydrodynamic film thickness, which in turninfluences the shear rate of the lubricant film and the amount ofasperity contact, if any, between the seal and shaft, and thereforeinfluences the magnitude of heat generated at the dynamic interface.Management of interfacial contact pressure is particularly important inapplications where the pressure of the environment is higher than thepressure of the lubricant.

The flexing lip construction of dynamic sealing lip 127 relieves some ofthe contact pressure at the interface between the dynamic sealing lip127 and the relatively rotatable surface that would otherwise occur ifthe seal were of the direct compression type (such as the seal of FIG.3), thereby helping to assure sufficient hydrodynamic lubrication.

The seal of FIG. 4 may be composed of any suitable sealing material,including elastomeric or rubber-like materials and various polymericmaterials, and including different materials bonded together to form acomposite structure; however it is preferred that dynamic sealing lip127 be made from a reinforced material, such as multiple ply fabricreinforced elastomer.

In FIG. 5, the dynamic sealing lip 127 and the static sealing lip 128are made from a first material having a predetermined modulus ofelasticity, and the energizer 163 is made from a second material havinga modulus of elasticity that is less than that used to form the dynamicsealing lip 127 and the static sealing lip 128. The energizer 163 takesthe form of an insertable annular member, such as but not limited to anO-Ring, that is installed into annular recess 167.

In FIGS. 6 and 7, the dynamic sealing lip 127 and the static sealing lip128 are made from a sealing material having a predetermined modulus ofelasticity, and the energizer 163 is a spring having a modulus ofelasticity that is greater than that used to form the dynamic sealinglip 127 and the static sealing lip 128. In FIG. 6 the energizer 163 is aconventional seal-lip energizing coil spring, such as a canted coilspring or a garter spring, and in FIG. 7 the energizer 163 is aconventional seal-lip energizing cantilever spring-type member. Springsare highly desirable for use as energizers in hydrodynamic seals becausetheir high modulus of elasticity allows them to cause the dynamicsealing lip 127 to follow relatively high levels of shaft deflection andrunout, and because they are more resistant to high temperaturecompression set, compared to many elastomeric energizers.

In FIG. 8, the dynamic sealing lip 127 is made from a first resilientmaterial layer having a predetermined modulus of elasticity, and theenergizer 163 is made from a second material layer having a modulus ofelasticity that is typically less than that used to form the dynamicsealing lip 127. For example, a 40-80 durometer Shore A elastomer couldbe used to form the energizer 163, and a resilient material having ahardness greater than 80 durometer shore A could be used to form thedynamic sealing lip 127. Thus the extrusion resistance at the dynamicsealing lip 127 is controlled by its modulus of elasticity, but itsinterfacial contact pressure is controlled by the modulus of elasticityof the energizer 163. This provides good extrusion resistance, andrelatively low breakout torque and running torque. The low runningtorque minimizes running temperature, which moderates temperaturerelated seal degradation. The second seal end 136 is preferred to beconvex in the uninstalled condition. In FIG. 6, the energizer 163comprises the majority of the seal, so that the interfacial contactpressure is not dictated by the relatively higher modulus material ofthe dynamic sealing lip 127. The material interface between the materialforming the dynamic sealing lip 127 and the energizer 163 can be of anysuitable form.

It is widely understood that the higher the modulus of elasticity of thesealing material, the more resistant the seal is to high-pressureextrusion damage. In the seal of FIG. 8, and the seals of other figuresherein which employ an energizer having a lower modulus of elasticitycompared to the material of the dynamic sealing lip, the dynamic sealinglip is preferred to be constructed from a hard, relatively high modulusextrusion resistant material such as a flexible polymeric material, ahigh modulus elastomer such as one having a durometer hardness in therange of 80-97 Shore A, or a fabric, fiber or metal reinforcedelastomer, or a high performance temperature-resistant plastic.

It can be appreciated that benefits other than extrusion resistance andlowered torque can be provided by the dual material construction of theseals illustrated in this specification that employ an energizer. Forexample, it would be useful to employ a TFEP material to construct thedynamic sealing lip 127 in order to exploit it's excellent hightemperature crack and abrasion resistance, then use a more compressionset resistant material such as FKM or silicone to form the energizer 163in order to compensate for the poor compression set resistance of theTFEP.

In the seals of FIGS. 2-8, dynamic control surface 145 and staticcontrol surface 148 of annular seal body 104 are preferably provided toprevent undue twisting of the installed seal within the seal groove. InFIG. 9 the dynamic control surface and the static control surface havebeen eliminated all the way back to the dynamic sealing lip 127 as asimplification, leaving the first seal end 133 wavy; i.e. non-circular.This arrangement is particularly suitable for applications where thepressure of the second fluid is higher than the pressure of the firstfluid, or for applications that require the use of materials having poorcompression set, such as TFEP, where spring loading can be employed tohelp to compensate for compression set of the seal material. To bestexploit the seal of FIG. 9, the first groove wall can be made in a wavy,non-circular shape corresponding to the wavy shape of first seal end133. If the first groove wall is made wavy so that it inter-fits with,and supports the wavy shape of first seal end 133, then forces actingagainst either first seal end 133 or second seal end 136 cannotcompletely flatten hydrodynamic inlet curvature 142 against therelatively rotatable surface, thereby preserving an efficient, gentlyconverging hydrodynamic wedging angle between hydrodynamic inletcurvature 142 and the relatively rotatable surface for maintainingefficient hydrodynamic film lubrication of sloping dynamic sealingsurface 140. This makes the seal run much cooler than comparablenon-hydrodynamic seals, therefore the seal retains a relatively highmodulus of elasticity for optimum extrusion resistance. If the firstgroove wall is made wavy so that it inter-fits with, and supports thewavy shape of first seal end 133 dynamic exclusionary intersection 139is maintained in the intended substantially circular configuration forefficient environmental exclusion, despite forces acting against secondseal end 136 that, in the prior art, compromise the performance of suchexclusionary intersections.

In conditions of differential pressure acting from the direction of thesecond end 136, the wavy shape of the first groove wall supports theseal against the distorting effect of the pressure of the second fluidto maintain the functional integrity of the hydrodynamic inlet curvature142 and the dynamic exclusionary intersection 139. In applications wherehigh compression set sealing materials such as TFEP must be used inconjunction with spring force to negate some of the compression set, thewavy shape of the first groove wall maintains the wavy positionalvariations of the hydrodynamic inlet curvature 142 despite the poorcompression set resistance of the material.

The seal of FIG. 9 may be composed of any suitable sealing material,including elastomeric or rubber-like materials and various polymericmaterials, and including different materials bonded together to form acomposite structure or inter-fitted together; however it is preferredthat the portion of the seal defining dynamic sealing lip 127 be madefrom a reinforced material, such as multiple ply fabric reinforcedelastomer having at least some of the plies substantially aligned withsloping dynamic sealing surface 140.

The fragmentary transverse cross-sectional views of FIG. 10 shows thatthe variable hydrodynamic geometry can be on both sealing lips, ratherthan having a static sealing lip and a dynamic sealing lip. This allowsthe seal to slip in a hydrodynamically lubricated mode with either therelatively rotatable surface, the seal groove, or both.

In FIG. 10, two dynamic sealing lips are provided; first dynamic lip127A and second dynamic lip 127B and they define respective first andsecond sloping dynamic sealing surfaces 140A and 140B.

When the seal of FIG. 10 is installed between a relatively rotatablesurface and a circular seal groove, both of the first and second dynamiclips 127A and 127B establish variable width interfacial contactfootprints with their respective counter-surfaces, wherein the widthdimension of each footprint varies in size about the circumference ofthe seal.

When the seal of FIG. 10 is installed, the first footprint edge of eachof the interfacial contact footprints is non-circular; i.e. wavy, and inconjunction with the deformed shape of the seal, produces a hydrodynamicwedging action in response to any relative rotation between the seal andthe respective counter-surfaces of the seal groove and the relativelyrotatable surface.

Although FIGS. 3-10 show seals for sealing against an externalcylindrical surface, the basic cross-sectional configurations areequally suitable for being oriented for face sealing, or for sealingagainst an internal cylindrical surface.

The basic sealing elements shown herein (exclusive of the energizerswhich are discussed separately) may be composed of any of a number ofsuitable materials, or combinations thereof, including elastomeric orrubber-like sealing material and various polymeric sealing materials.

As with the preferred embodiment, for all of the seals illustrated inthe figures herein, the depth dimension D may if desired vary in timewith the varying position of the hydrodynamic inlet curvature (and theresulting variation in width dimension W of the interfacial contactfootprint) to help even out interfacial contact pressure variationsaround the circumference of the seal.

In view of the foregoing it is evident that the present invention is onewell adapted to attain all of the objects and features hereinabove setforth, together with other objects and features which are inherent inthe apparatus disclosed herein.

As will be readily apparent to those skilled in the art, the presentinvention may easily be produced in other specific forms withoutdeparting from its spirit or essential characteristics. The presentembodiment is, therefore, to be considered as merely illustrative andnot restrictive, the scope of the invention being indicated by theclaims rather than the foregoing description, and all changes which comewithin the meaning and range of equivalence of the claims are thereforeintended to be embraced therein.

We claim:
 1. A hydrodynamic seal (103) for sealing between a firstmachine component (109) and a relatively rotatable surface (115) of asecond machine component (118) and for serving as a partition between afirst fluid (121) and a second fluid (124) and preventing intrusion ofthe second fluid (124) into the first fluid (121), comprising: A. anannular seal body (104) having a first seal end (133) and a second sealend (136); B. an annular static sealing lip (128) defining an annularsloping static sealing surface (131) establishing compressed sealingrelation with the first machine component (109); C. an annular dynamicsealing lip (127) in generally opposed relation to said annular staticsealing lip (128) and defining: i. a sloping dynamic sealing surface(140) of generally annular form and having variable width and being forestablishing compressed sealing relation with the relatively rotatablesurface (115); ii. a hydrodynamic inlet curvature (142) that varies inposition relative to said second seal end (136) to form one or morewaves for providing hydrodynamic wedging action in response to relativerotation; iii. a dynamic exclusionary intersection (139) ofsubstantially abrupt form for facing and preventing intrusion of thesecond fluid (124); and iv. said sloping dynamic sealing surface (140)being located between said hydrodynamic inlet curvature (142) and saiddynamic exclusionary intersection (139).
 2. The hydrodynamic seal (103)of claim 1, comprising: at least one energizer (163) of generallycircular form for loading said sloping dynamic sealing surface (140)into compressed sealing relation with the relatively rotatable surface(115).
 3. The hydrodynamic seal (103) of claim 2, comprising: said atleast one energizer (163) being an elastomeric ring.
 4. The hydrodynamicseal (103) of claim 2, comprising: said at least one energizer (163)being at least one cantilever-type spring.
 5. The hydrodynamic seal(103) of claim 2, comprising: said at least one energizer (163) being acanted coil spring.
 6. The hydrodynamic seal (103) of claim 2,comprising: said at least one energizer (163) being a garter coilspring.
 7. The hydrodynamic seal (103) of claim 2, comprising: said atleast one energizer (163) being located between said annular dynamicsealing lip (127) and said annular static sealing lip (128).
 8. Thehydrodynamic seal (103) of claim 2, comprising: said at least oneenergizer (163) defining said annular static sealing lip (128).
 9. Thehydrodynamic seal (103) of claim 2, comprising: said at least oneenergizer (163) having a modulus of elasticity less than the modulus ofelasticity of said annular seal body (104).
 10. The hydrodynamic seal(103) of claim 2, comprising: said at least one energizer (163) having amodulus of elasticity greater than the modulus of elasticity of saidannular seal body (104).
 11. The hydrodynamic seal (103) of claim 1,comprising: said dynamic exclusionary intersection (139) being anintersection between said sloping dynamic sealing surface (140) and saidsecond seal end (136).
 12. The hydrodynamic seal (103) of claim 1,comprising: said second seal end (136) projecting outward in a generallyconvex configuration in the uncompressed condition thereof.
 13. Thehydrodynamic seal (103) of claim 1, wherein: A. said annular seal body(104) defining a depth dimension (D) from said annular sloping staticsealing surface (131) to said sloping dynamic sealing surface (140); B.said annular seal body (104) defining a length dimension (L) from saidfirst seal end (133) to said second seal end (136); C. the ratio of saidlength dimension (L) divided by said depth dimension (D) being greaterthan 1.2; D. said annular seal body (104) defining a dynamic controlsurface (145) facing the relatively rotatable surface (115) andresisting cross-sectional twisting of said annular seal body (104); E.said annular seal body (104) defining a static control surface (148)facing the first machine component (109) and resisting cross-sectionaltwisting of said annular seal body (104); and F. said dynamic controlsurface (145) and said static control surface (148) being in generallyoppositely oriented relation to one another.
 14. The hydrodynamic seal(103) of claim 1, wherein: A. said annular seal body (104) defining adepth dimension (D) from said annular sloping static sealing surface(131) to said sloping dynamic sealing surface (140); B. said annularseal body (104) defining a length dimension (L) from said first seal end(133) to said second seal end (136); C. the ratio of said lengthdimension (L) divided by said depth dimension (D) being in the range of1.4 to 1.6; D. said annular seal body (104) defining a dynamic controlsurface (145) facing the relatively rotatable surface (115) andresisting cross-sectional twisting of said annular seal body (104); E.said annular seal body (104) defining a static control surface (148)facing the first machine component (109) and resisting cross-sectionaltwisting of said annular seal body (104); and F. said dynamic controlsurface (145) and said static control surface (148) being in generallyoppositely oriented relation to one another.
 15. The hydrodynamic seal(103) of claim 1, wherein: A. said annular seal body (104) defining adepth dimension (D) from said annular sloping static sealing surface(131) to said sloping dynamic sealing surface (140); and B. themagnitude of said depth dimension (D) varying substantially in time withsaid position of said hydrodynamic inlet curvature (142).
 16. Thehydrodynamic seal (103) of claim 1, wherein: said second seal end (136)defining an annular recess (167) intermediate said annular dynamicsealing lip (127) and said annular static sealing lip (128).
 17. Thehydrodynamic seal (103) of claim 1, wherein: said first seal end (133)varying in position relative to said second seal end (136) andsubstantially in time with said position of said hydrodynamic inletcurvature (142).
 18. The hydrodynamic seal (103) of claim 1, wherein:said annular seal body (104) being solid in cross-section.
 19. Thehydrodynamic seal (103) of claim 1, wherein: A. said annular dynamicsealing lip (127) projecting radially inward from said annular seal body(104); and B. said annular static sealing lip (128) projecting radiallyoutward from said annular seal body (104).
 20. The hydrodynamic seal(103) of claim 1, wherein: A. said annular dynamic sealing lip (127)projecting radially outward from said annular seal body (104); and B.said annular static sealing lip (128) projecting radially inward fromsaid annular seal body (104).
 21. The hydrodynamic seal (103) of claim1, wherein: said annular dynamic sealing lip (127) and said annularstatic sealing lip (128) both projecting axially from said annular sealbody (104).
 22. A hydrodynamic seal (103) for sealing between a firstmachine component (109) and a relatively rotatable surface (115) and forserving as a partition between a first fluid (121) and a second fluid(124) and preventing intrusion of the second fluid (124) into the firstfluid (121), comprising: A. an annular seal body (104) having a firstseal end (133) and a second seal end (136); B. a first annular dynamicsealing lip (127A) for establishing compressed sealing relation with therelatively rotatable surface (115) and defining: i. a first dynamicsealing surface (140A) of generally annular form and having variablewidth and being for establishing compressed dynamic sealing relation anda first dynamic sealing interface with the relatively rotatable surface(115); ii. a first hydrodynamic inlet curvature (142A) that varies inposition relative to said second seal end (136) to form one or morewaves for providing hydrodynamic wedging action in response to relativerotation of said first dynamic sealing surface (140A) and the relativelyrotatable surface (115); and iii. a first dynamic exclusionaryintersection (139A) of substantially abrupt form being in contact withthe relatively rotatable surface (115) and facing and preventingintrusion of the second fluid (124) into the first fluid (121); C. asecond annular dynamic sealing lip (127B) in generally opposed relationto said first annular dynamic sealing lip (127A) for establishingcompressed dynamic sealing relation with the first machine component(109) and defining: i. a second dynamic sealing surface (140B) ofgenerally annular form being disposed in generally opposed relation withsaid first dynamic sealing surface (140A) and having variable width andbeing for establishing compressed dynamic sealing relation and a seconddynamic sealing interface with the first machine component (109); ii. asecond hydrodynamic inlet curvature (142B) that varies in positionrelative to said second seal end (136) to form one or more waves forproviding hydrodynamic wedging action in response to relative rotationof said second annular dynamic sealing lip (127B) and the first machinecomponent (109); and iii. a second dynamic exclusionary intersection(139B) of substantially abrupt form for contact with the first machinecomponent (109) and facing and preventing intrusion of the second fluid(124) into the first fluid (121).
 23. An annular hydrodynamic seal (103)for sealing between a groove counter-face (112) of first machinecomponent (109) and a second machine component (118) having a relativelyrotatable surface (115) and serving as a partition between first andsecond fluids (121, 124) and preventing intrusion of the second fluid(124) into the first fluid (121), comprising: A. an annular seal body(104) having first (133) and second (136) seal ends; B. a dynamicsealing lip (127) of generally circular configuration extending fromsaid annular seal body (104) and defining a sloping dynamic sealingsurface (140) of variable width and having a hydrodynamic inletcurvature (142) of variable position, said sloping dynamic sealingsurface (140) and said hydrodynamic inlet curvature (142) converging andestablishing an annular blend location (141); C. a static sealing lip(128) of generally circular configuration extending from said annularseal body (104) and being located in generally opposed relation withsaid dynamic sealing lip (127), said static sealing lip (128) defining asloping static sealing surface (131); D. said sloping dynamic sealingsurface (140) and said hydrodynamic inlet curvature (142) of saiddynamic sealing lip (127) being deformed by compressive engagement withthe relatively rotatable surface (115) and defining a hydrodynamicwedging angle and an interfacial contact footprint with respect to therelatively rotatable surface (115), said interfacial contact footprinthaving a first footprint edge (157) and a second footprint edge (160),said first footprint edge (157) being of non-circular configuration forhydrodynamically wedging a lubricating film of the first fluid (121)into said interfacial contact footprint responsive to relativerotational velocity, causing the lubricating film to migrate toward saidsecond footprint edge (160); and E. said sloping static sealing surface(131) having a lubricant side edge (132) and said sloping dynamicsealing surface (140) having a lubricant side edge defined by blendlocation (141), said sloping static sealing surface (131) and saidsloping dynamic sealing surface (140) having a converging relationshipon the sides thereof facing said lubricant side edge (132) and saidblend location (141), respectively.
 24. The annular hydrodynamic seal(103) of claim 23, comprising: said dynamic sealing lip (127) having adynamic exclusionary intersection (139) with said second seal end (136)and defining said second footprint edge (160) and being of substantiallycircular configuration for preventing hydrodynamic wedging action atsaid second seal end for excluding entry of the second fluid (124) intosaid interfacial contact footprint.
 25. The annular hydrodynamic seal(103) of claim 23, comprising: said second seal end (136) being ofgenerally convex geometry in the uncompressed state thereof and beingdeformed to a substantially planar geometry responsive to compression ofsaid annular hydrodynamic seal (103) between the groove counter-face(112) of the first machine component (109) and the relatively rotatablesurface (115).
 26. The annular hydrodynamic seal (103) of claim 23,comprising: said sloping dynamic sealing surface (140) and said slopingstatic sealing surface (131) each being disposed in angulated relationrespectively with the relatively rotatable surface (115) and the groovecounter-face (112) of said first machine component (109).
 27. An annularhydrodynamic seal (103) for establishing sealing between first andsecond relatively rotatable members (109, 118) and serving as apartition between a first fluid (121) and a second fluid (124) andpreventing intrusion of the second fluid (124) into the first fluid(121), comprising: A. an annular seal body (104) having a first seal end(133) and a second seal end (136); B. a dynamic sealing lip (127) beingintegral with said annular seal body (104) and defining at least oneannular sloping dynamic sealing surface (140) establishing dynamicexclusionary intersection (139) with said second seal end (136); C. saidat least one annular sloping dynamic sealing surface (140) of saiddynamic sealing lip (127) being deformed by compressive engagement withthe second relatively rotatable member (118) and defining a dynamicsealing interface having an interfacial contact footprint having a firstfootprint edge (157) and a second footprint edge (160) and varying inwidth (W); D. said at least one annular sloping dynamic sealing surface(140) defining a hydrodynamic wedging angle with respect to the secondrelatively rotatable member (118) for hydrodynamically wedging alubricating film of the first fluid (121) into said dynamic sealinginterface in response to relative rotational velocity, causing thelubricating film to migrate within said dynamic sealing interface towardthe second footprint edge (160); E. an annular static sealing lip (128)extending from said annular seal body (104) and being disposed ingenerally oppositely facing relation with said dynamic sealing lip(127), said annular static sealing lip (128) defining an annular slopingstatic sealing surface (131) establishing static exclusionaryintersection (151) with said second seal end (136); and F. said annularsloping static sealing surface (131) of said annular static sealing lip(128) being deformed by compressive engagement with the first relativelyrotatable member (109) and defining a generally circular staticinterfacial contact footprint with the first relatively rotatable member(109), the generally circular static interfacial contact footprinthaving first and second footprint edges.
 28. The annular hydrodynamicseal (103) of claim 27, comprising: said interfacial contact footprintof said annular dynamic sealing lip (127) having greater interfacialcontact pressure at said second footprint edge (160) resulting fromdeformation of said at least one annular sloping dynamic sealing surface(140) as compared with interfacial contact pressure at said firstfootprint edge (157).
 29. The annular hydrodynamic seal (103) of claim27, comprising: at least one energizer element (163) loading said atleast one annular sloping dynamic sealing surface (140) against thesecond relatively rotatable member (118) and establishing desiredinterfacial contact pressure therewith.
 30. The annular hydrodynamicseal (103) of claim 27 comprising: A. said annular seal body (104)defining a dynamic control surface (145) and a static control surface(148) being in substantially opposite facing relation with said dynamiccontrol surface (145), said dynamic and static control surfacesresisting interference compression induced cross-sectional twisting ofsaid annular seal body (104) and preserving interfacial contact pressureat said second footprint edge (160); B. said annular seal body (104)defining a depth dimension (D) from said annular sloping static sealingsurface (131) to said at least one annular sloping dynamic sealingsurface (140); C. said annular seal body (104) defining a lengthdimension (L) from said first seal end (133) to said second seal end(136); and D. the ratio of said length dimension (L) divided by saiddepth dimension (D) being greater than 1.2.
 31. An annular hydrodynamicseal (103) for interference sealing between a first machine component(109) and a second machine component (118) having a relatively rotatablesurface (115) and defining a sealed partition between a lubricantchamber of the first machine component (109) having a first fluid (121)and an environment having a second fluid (124), comprising: A. anannular seal body (104) having a first seal end (133) and a second sealend (136); B. an annular dynamic sealing lip (127) being defined by saidannular seal body (104) having an annular dynamic sealing surface (140)of sloped configuration; C. said second seal end (136) of said annularseal body (104) establishing dynamic exclusionary intersection (139)with said annular dynamic sealing surface (140); and D. upon compressionof said annular seal body (104) between said first machine component(109) and the relatively rotatable surface (115) at least a portion ofsaid annular dynamic sealing surface (140) being deformed by andassuming the configuration of the relatively rotatable surface (115) andestablishing a dynamic sealing footprint of varying width throughout thecircumference thereof; and E. an annular static sealing lip (128) beingdefined by said annular seal body (104) and having an annular slopedstatic sealing surface (131) establishing static exclusionaryintersection with said second seal end (136), said annular staticsealing lip (128) being deformed by interference compression with thefirst machine component (109) to define a static sealing interface withthe first machine component (109).
 32. The annular hydrodynamic seal(103) of claim 31, comprising: an energizer (163) being located withinsaid annular seal body (104) and being located intermediate said annulardynamic sealing lip (127) and said annular static sealing lip (128) andrespectively loading said dynamic and static sealing lips (127, 128)against the relatively rotatable surface (115) and the first machinecomponent (109) respectively.
 33. The annular hydrodynamic seal (103) ofclaim 32, comprising: A. said second seal end (136) of said annular sealbody (104) defining an annular recess (167); and B. said energizer (163)being located within said annular recess (167).
 34. The annularhydrodynamic seal (103) of claim 32, comprising: said energizer (163)being an annular spring of generally C-shaped cross-sectionalconfiguration.
 35. The annular hydrodynamic seal (103) of claim 32,comprising: said energizer (163) being an annular member composed of anelastomer material having a modulus of elasticity less than the modulusof elasticity of said annular seal body (104).
 36. A hydrodynamic seal(103) for sealing between a first machine component (109) and a secondmachine component (118) having a relatively rotatable surface (115) andserving as a partition between a first fluid (121) and a second fluid(124) and preventing intrusion of the second fluid (124) into the firstfluid (121), comprising: A. an annular seal body (104) having a firstseal end (133) and a second seal end (136); B. an annular static sealinglip (128) defining a static sealing surface (131) for establishingcompressed sealing relation with the first machine component (109); C.an annular dynamic sealing lip (127) in generally opposed relation tosaid annular static sealing lip (128) for establishing compressedsealing relation with the relatively rotatable surface (115) anddefining: i. a dynamic sealing surface (140) of generally annular formand having variable width and being for establishing compressed sealingrelation with the second machine component (118); ii. a hydrodynamicinlet curvature (142) that varies in position relative to said secondseal end (136) to form at least one wave for providing hydrodynamicwedging action in response to relative rotation; and iii. a dynamicexclusionary intersection (139) of substantially abrupt form for facingand preventing intrusion of the second fluid (124) into the first fluid(121), D. said annular seal body (104) defining a depth dimension D fromsaid static sealing surface (131) to said dynamic sealing surface (140);and E. the magnitude of said depth dimension D varying substantially intime with said position of said hydrodynamic inlet curvature (142). 37.A hydrodynamic seal (103) for sealing between a first machine component(109) and a second machine component (118) having a relatively rotatablesurface (115) for serving as a partition between a first fluid (121) anda second fluid (124) and for preventing intrusion of the second fluid(124) into the first fluid (121), comprising: A. an annular seal body(104) having a first seal end (133) and a second seal end (136), saidsecond seal end being of generally convex configuration; B. an annulardynamic sealing lip (127) for establishing compressed sealing relationwith the relatively rotatable surface (115) and defining: i. a dynamicsealing surface (140) of generally annular form and having variablewidth for establishing compressed sealing relation with the relativelyrotatable surface (115); ii. a hydrodynamic inlet curvature (142) thatvaries in position relative to said second seal end (136) and defines atleast one wave for providing hydrodynamic wedging action in response torelative rotation; and iii. a dynamic exclusionary intersection (139) ofsubstantially abrupt form facing the second fluid (124) and forpreventing intrusion of the second fluid (124) into the first fluid(121).